If a mother is type ab+ and a father is type o- what are the chances their children will be type o+?

The chances of their children being 0+ is 50%.

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds

the correct answer is 2 and 4