Construction sites are dangerous as there are numerous hazards there, that's why the construction site safety signs are put in place in order to minimize the risk of injuries and accidents.
Based on the information given, the correct option is D since all the options given are correct.
Some of the shapes or signs that are used in construction sites in order to prevent accidents include:
• the presence of a flagger.
• orange and diamond shaped work signs.
• a sign with an arrow flashing panel.
It should be noted that the reason why orange color is used is to ensure visibility, that's why a bright color is used in order to prevent accidents. Some of the signs can be shown in a picture or through written words that shows that there's road work ahead.