Mosquito Feeding in Malaria Transmission Cycle

Steps:

• Uninfected mosquito feeds on infected human, ingesting gametocytes that undergo sexual reproduction in its gut.
• Parasites develop through sporogonic cycle in mosquito's salivary glands over 10-18 days, making it infectious.
• Infectious mosquito must feed again on uninfected human to inject sporozoites via saliva.
• This second feed transmits the parasite, completing human-to-human spread.

Why B is correct:

• Malaria transmission requires the mosquito to acquire parasites via one blood meal from an infected host before delivering them in a subsequent meal, per the Plasmodium life cycle.

Why the others are wrong:

• A: Only once fails because an uninfected mosquito cannot transmit without first ingesting parasites.
• C: At least three is excessive; the second feed suffices for transmission after parasite maturation.
• D: More than three is unnecessary; two feeds enable infection of a new host.

Final answer: B