A) Soil pH is a characteristic that describes the relative acidity or alkalinity of the soil of the Soils are considered acidic below a pH of 5, and very acidic below a pH of 4. Conversely, soils are considered alkaline above a pH of 7.5 and very alkaline above a pH of 8
B) While there's logic in that, dogs don't just love treats, they also love new treats. Most dogs get very excited at the sight of a new treat even if the old one is still their favorite. Keep giving them the old ones as well if they prefer it, but also add a little diversity of a they be grateful
C) the important meeting one whose outcome affects you and your team the after it happens. When you’re overlooked for a meeting it feels bad personally and professionally
D) the long term running changes your vascular system; your heart size grows, the heartbeat rate decreases and your arteries widen. They may get harder with the build up of plaque as the studies indicate, but it's not clear that that's a bad thing

Answer:
the answer is option D : 4
1. The appearances of fireflies at dusk is an example of a circadian rhythm because it's happens daily. The correct option among all the options that are given in the question is the third option or option "c".
2. During migration, animals undertake a seasonal movement. The correct option among all the options that are given in the question is the first option or option "a".