Milkweed, tobacco, and poison ivy plants have adapted what type of measures to protect themselves?

These plants have adapted chemical measures to protect themselves.

Explanation:

Milkweed:

It has ability to protect itself. They produce sandpapery leaves (toxins) that can stop human heart. For insects they produce a poison which glue their mouth of insects.  

Tobacco:

Its leaves emit a chemical. When hornworm caterpillars eat these leaves then that chemical mixed with their spit and they doom into their own spit.  

Poison Ivy:

This plant has a skin irritant and use this irritant to protect itself from caterpillars and slugs.

Hence, these plants use chemicals for their defense.

1 a

2 b

3 b

4 d

5 d

6 d

explanation:

where is the circuit diagram ?