a) 

Assertion (A): Only angiosperms undergo double fertilization.

Reason (R): In Asexual reproduction, triple fusion occurs.               

                                                                                              

     b)                                                                                           OR             

 Assertion (A): The most effective form of contraception is the surgical method.

Reason (R): The surgical procedure stops the passage of gametes, which stops fertilization.                                                                      

a) 

The assertion is true, and the reason is the correct explanation.

●      Because the ovary develops into fruit and the ovule develops into a seed with an embryo and primary endosperm inside of it, double fertilisation is regarded as a singular event in the plant kingdom.

●  One male gamete joins the egg cell during double fertilisation to create a diploid zygote.

Only angiosperms have triple fusion

●      The fertilisation of the two polar nuclei in the embryo sac is called triple fusion.

●      It happens when angiosperms undergo double fertilisation.

●      The two polar nuclei present in the core cell of the embryo are fertilised by one sperm cell, while the egg cell in the embryo sac is fertilised by the other sperm cell.

●      One male gamete fuses the female gamete, while the other male gamete fuses the secondary nucleus.

 ●      This method is known as double fertilisation because it involves two male gametes and results in double fertilisation.

●      The process is known as triple fusion because it involves three gametes.

●      Therefore, the assertion is true.

Hence option (a) Both A and R are true, and R is the correct explanation of the assertion is correct.

  b)                                                                                              OR

Both A and R are correct, and R is the correct explanation of A

Assertion: Surgical methods prevent conception. The different surgical methods are

●      Tubectomy

●      Vasectomy

●      Orchiectomy

●      Oophorectomy

(a)  Tubectomy: Tubectomy is a sterilisation procedure in women. In this process, the female's fallopian tube is cut and tied. This blocks the transportation of the ovum from the ovaries to the uterus, thereby eliminating any chances of pregnancy.

(b)  Vasectomy: In this process, the male's vas deferens are cut and tied. This blocks the sperms' pathway; therefore, the sperms cannot reach the urethra via the ejaculatory duct.

(c)   Orchiectomy: One or both testicles are surgically removed in this process.

(d)  Oophorectomy: One or both ovaries are surgically removed in this process.

Hence, surgical intervention blocks gamete production and transport, thereby preventing conception.

The reason is the correct explanation of the assertion.