Why Has It Been Difficult to Make a Vaccine Against

question 31

Multiple Choice

Why has it been difficult to make a vaccine against HIV?

• A) The vaccine is too expensive.
• B) The vaccine is as dangerous to work with as HIV.
• C) The protein coat of an infected cell always looks the same to the immune system.
• D) The HIV virus mutates too quickly for a vaccine to be effective.

---

Definitions:

Moving Objects

Refers to items or things that are being transported or shifted from one place to another.

Months of Age

A way to measure age primarily used for infants and young children that denotes the number of months since birth.

Motor Development

Refers to the progression of muscular coordination, strength, and the ability to move through and interact with one’s surroundings.

Physical Capacities

The abilities related to physical condition and performance, including strength, flexibility, endurance, and coordination.