Market efficiency is probably the most controversial concept in finance. Even recent winners of the Nobel Prize in Economics come down on opposite sides of the issue. Nonetheless, it is important for you to grapple with this idea. It has very important practical implications for investment decisions, including (especially) for your personal investment decision. In particular, should you pursue active or passive strategies

Active strategies should be pursued when the market is more volatile, with larger fluctuations over a shorter period of time, that require a more active management of a portfolio, in order to take advantage of fast changing positions in different assets, and also in order to avoid possible losses due to staying in particular positions for too long.

Passive strategies is more long-term focused, and should be pursued when the economy is more stable. Passive strategies should be analyzed carefully before execution because once the passive investment is made, the idea is to keep the position for a long period of time instead of buying and selling constantly as in a active strategy.

d) social security number

let me know if i am correct or not, so i can edit the answer.

answer; at prices that violate government price regulations;