Final answer:
To prevent tailing or streaking in the distillation of petroleum fractions, adjusting the heating intensity is the most effective method, as it ensures proper vaporization and separation of hydrocarbons without causing overlap in the vaporization of compounds with different boiling points.
Step-by-step explanation:
To prevent tailing or streaking in a petroleum distillation tower, which is the separation of petroleum fractions based on their boiling points, one must control the operational conditions carefully. Adjusting heating intensity (option a) may help because if the heat is too high it can cause components with different boiling points to vaporize together, leading to tailing. However, using narrower columns (option b) is not typically a method to prevent tailing; the column diameter is designed based on throughput and desired separation efficiency.
Increasing pressure (option c) in the system can raise the boiling points of the fractions, but it does not directly prevent tailing or streaking unless it corrects an issue of the vapors not rising correctly through the trays. Finally, shortening the distillation time (option d) is not practical or effective since the time required for distillation is determined by the rate at which the separate fractions condense and are collected.
Thus, the most relevant options for preventing tailing or streaking would involve careful control of the heating intensity to ensure that the vaporization process works as intended, allowing for proper separation of the different hydrocarbons.